Without the application of finishing components, most cotton fabrics and cotton blend fabrics have a handle appearance that is rather hard and stiff. The fabric surface also is not smooth because small fuzzy microfibrils protrude from it. In addition, after a relatively short period of wear, pilling appears on the fabric surface thereby giving it an unappealing, worn look.
A high degree of fabric softness and smoothness can be obtained by using fine (low-denier) yarns in weaving. However, the resulting cost is high as the loom output decreases concurrently with the (weft) yarn diameter.
A less expensive way of ensuring a soft and smooth fabric "handle" is to impregnate the finished fabric with a softening agent, typically a cationic, sometimes silicone-based, surface active compound. This treatment also has some functional disadvantages. It does not remove pills and fuzz. The fabric obtains a somewhat greasy "handle" and its moisture absorbency is often considerably reduced, which is a great disadvantage, especially with towels and underwear. Moreover, the fabric is not wash-proof.
Another method for obtaining a soft and smooth fabric is subjecting cellulosic fabrics to treatment by cellulytic enzymes during their manufacture. This treatment is known as Bio-Polishing.
Bio-Polishing is a specific treatment of the yarn surface which improves fabric quality with respect to handle and appearance without loss of fabric wettability. The most important effects of Bio-Polishing can be characterized by less fuzz and pilling, increased gloss/luster, improved fabric handle, increased durable softness and improved water absorbency.
Bio-Polishing usually takes place in the wet processing of the manufacture of knitted and woven fabrics. Wet processing comprises such steps as e.g. desizing, scouring, bleaching, washing, dyeing/printing and finishing. During each of these steps, the fabric is more or less subjected to mechanical action.
In general, after the textiles have been knitted or woven, the fabric proceeds to a desizing stage, followed by a scouring stage, etc. Desizing is the act of removing size from textiles. Prior to weaving on mechanical looms, warp yarns are often coated with size starch or starch derivatives in order to increase their tensile strength. After weaving, the size coating must be removed before further processing the fabric in order to ensure a homogeneous and wash-proof result. The preferred method of desizing is enzymatic hydrolysis of the size by the action of amylases.
It is known that in order to achieve the effects of Bio-Polishing, a combination of enzymatic action and mechanical action is required. It is also known that if the enzymatic treatment is combined with a conventional treatment with softening agents, "super-softness" is achievable.
It was hitherto believed that enzymatic and mechanical action had to take place simultaneously and that the effect of enzymatic action ceased once the enzyme became inactivated. Consequently, the enzymatic action and the mechanical action hitherto have been carried out in a single separate step of the manufacturing process as a batch process, e.g. in a high-speed circular system such as "jet/overflow" dyeing machines and high-speed winches, where a combination of enzymatic and mechanical action can be obtained. Bio-Polishing, therefore, could be incorporated into existing continuous fabric manufacturing process only with great difficulty.
It is the object of the present invention to provide a process for achieving Bio-Polishing effects which (1) can be implemented in existing processes and in existing apparatus, (2) can be adapted to continuous processes and (3) is time saving.